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Crop the centre before resizing for fit=cover (closes #282) #284

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clawbot merged 6 commits from issue-282-cover-crop-first into next 2026-10-16 02:23:19 +02:00
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6 Commits
Author SHA1 Message Date
sneak ea77bdfa63 Scale both sides of a fit=cover image by the same amount (part of #282)
check / check (push) Waiting to run
Details 
cropCentreAndResize cut the centre to whole source pixels and forced
that to the requested size, so the two sides were scaled by different
amounts: a 16x16 source at 100x60 came out squashed by 4%. It now
widens the centre to whole source pixels and lets thumbnail with a
centre crop scale that by the one amount next uses and cut the output
from it. thumbnail copies the scaled image into memory, which is larger
than the output by less than one scaled source pixel on each side.
TODO.md says so.

Model: opus-5-5
 2026-10-15 23:39:38 +00:00
sneak eaac8fd7cf Test that fit=cover keeps the source's proportions (part of #282) 
A grey square in the centre of the source must come out square: a
16x16 source at 100x60, a 10x10 one at 100x35 and a 64x64 one at
300x100, and each turned on its side. The square's width and height
are measured where its blurred edges cross the grey halfway between
the square's and the background's, read to a fraction of a pixel.

Model: opus-5-5
 2026-10-15 23:39:24 +00:00
sneak 70631def34 Drop the fit=cover test cases that fill memory without the fix (part of #282) 
Without the fix, the 8192x64 and 64x8192 cases each made libvips ask for
about 24 GiB, so a return of the bug would take the build host's memory
instead of failing the test. The cases left fail at once without the fix.

Model: opus-5-5
 2026-10-15 23:39:24 +00:00
sneak 4d59886082 Test that fit=cover serves a source whose centre is under a pixel wide (part of #282) 
An 8192x1 source at 1x8192, or the same turned on its side, has a centre
with the requested proportions 1/8192 of a pixel wide. The crop must keep
at least one pixel of it, or the request fails. The test's cases are now
named by source and requested size.

Model: opus-5-5
 2026-10-15 23:39:24 +00:00
sneak 96d5ccf5cc Crop the centre first for fit=cover (closes #282) 
libvips' thumbnail with a centre crop scales the whole source to cover
the requested size and copies that into memory before it crops: 8192x64
at 8192x8192 made it allocate about 24 GiB, and 8192x1 failed with 500.
resize now cuts the centre of the source to the requested size's
proportions first and resizes that, so no image larger than the source
or the output is made. The crop is the same centre as before. TODO.md
says so.

Model: opus-5-5
 2026-10-15 23:39:24 +00:00
sneak fb33a3bb34 Test that fit=cover serves a thin source and keeps its centre (part of #282) 
An 8192x64 or 8192x1 source, or one turned on its side, requested at
8192x8192 with fit=cover must be served at that size, and fit=cover must
keep the centre of an ordinary source.

Model: opus-5-5
 2026-10-15 23:39:24 +00:00